--> Quantifying Facies Attributes of the Caicos Platform, by Paul M. (Mitch) Harris and Brigitte M. Vlaswinkel, #50079 (2008).

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PSQuantifying Facies Attributes of the Caicos Platform*


Paul M. (Mitch) Harris1 and Brigitte M. Vlaswinkel2


Search and Discovery Article #50079 (2008)

Posted August 1, 2008


*Adapted from poster presentation at AAPG Annual Convention, San Antonio, Texas, April 20, 2008. See companion articles, “Trend Metrics of Modern Carbonate Depositional Systems,” Search and Discovery Article #50081 (2008) and “Input for Carbonate Reservoir Models: Trend Metrics of Modern Platforms and Reef Systems,” Search and Discovery Article #50127 (2008).

Click to view list of articles adapted from presentations by P.M. (Mitch) Harris or by his co-workers and him at AAPG meetings from 2000 to 2008.

1Chevron Energy Technology Company, San Ramon, CA 94583 ([email protected])

2Shell International E&P, Rijswijk, 2288 GS, The Netherlands ([email protected])



Spatial heterogeneity is a basic characteristic of carbonate depositional systems. Examining spatial depositional patterns and quantifying the facies attributes (e.g., size, shape, and facies interrelationships) in modern analogs can decrease uncertainty in a geologic model and therefore enhance the model’s utility. In an attempt to gather such valuable data, the attributes for key facies of the Caicos platform are assessed from a Landsat image through facies mapping. Reef-associated facies, including fully aggraded reef, partially aggraded reef, and apron are emphasized due to their importance in many isolated platform reservoirs.


Some key findings are:

1. Platform size and reef abundance are directly related, wherein reef (fully and partially aggraded) and reef apron occupy a smaller percentage of a large platform like Caicos.

2. Reefs seem to be patchier than aprons.

3. Fully aggraded reefs become somewhat wider as their length increases; partially aggraded reefs are discontinuous along their long axis so the relation to reef width is more subtle.

4. Reef width and apron width are directly related.

5. Probabilities can be set for expected dimensions for: reef width (10% probability that reef width > 410 m, 50% probability > 270 m, and 90% probability > 145 m); and apron width (10% probability that apron width > 945 m, 50% probability > 395 m, and 90% probability > 90m).


Modern analogs like Caicos can play an important role as conceptual facies models for characterization of a reservoir, and also in providing facies attribute information to be used as input in building reservoir models






























































Selected Figures

Landsat image (left) and facies interpretation (right) of the Caicos platform.

Seismic profile (left) and depositional model (right) of Malampaya, which is an isolated carbonate platform with a reef rim and an asymmetric facies distribution over the platform (from Grötsch and Mercadier, 1999).

Data grouped by size and shape.


Attribute data from reef facies, shown graphically.

A. Reef width vs. total length. Fully aggraded reefs generally become wider as their long axis increases, but the relation is more subtle for the more discontinuous, partially aggraded reefs (left).Fully aggraded reef, Caicos platform (center). Partially aggraded reef, Caicos platform (right).

B. Apron width vs. reef width, Caicos platform, which shows strong positive relation between width of the reef (reef is fully or partially aggraded) and the apron..

C. Exceedance probability plots from all platforms, with Caicos being the largest, show size attributes for reef width (left) and apron width (right).



  • An accurate facies model is essential for reservoir characterization and realistic reservoir modeling, as depositional facies can be a main parameter controlling heterogeneity in porosity and permeability.

  • Prediction of the quantitative attributes (size, shape, orientation, distribution, etc.) and variation of facies dimensions is fundamental for enhanced reservoir simulations for carbonate systems.



  • Provide an overview of the spectrum of facies patterns present in modern isolated carbonate systems.

  • Obtain quantitative data on facies dimensions, grouped by size and shape of carbonate platform.

  • Explore correlations and trends on landscape and facies scale.



1) Fully aggraded reef

2) Partially aggraded reef

3) Reef apron

4) Shoals

5) Shallow platform interior (w or w/o isolated reefs)

6) Intermediate platform interior (w or w/o reefs)

7) Deep platform interior (w or w/o reefs)

8) Forereef/outer platform

9) Land/exposed terrain



Grötsch, Jürgen, and Christophe Mercadier, 1999, Integrated 3-D reservoir modeling based on 3-D seismic: The Tertiary Malampaya and Camago buildups, offshore Palawan, Philippines: AAPG Bulletin, v. 83, p. 1703-1728.


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